PH Buffer Powder for FA Tester Calibration Solution Mixture PH 4 6.86 by CyberTech &#10004;Immerse the tester up to the maximum immersion level in the PH 4 or 6.86 buffer solution. (Package Includes 2 pack of PH substance which makes 250 ml buffer solutions, PH 4 or PH 6.86) &#10004;Allow the reading to stablilize and using the small screwdriver adjust the calibration trimmer to reading 6.9 &#10004;Package includes: 2x pH 4.00 and 2x pH 6.86